Nanoindentation Study Of Corrosion-Induced Grain Boundary Degradation In A Pipeline Steel, 2018 Iowa State University
Nanoindentation Study Of Corrosion-Induced Grain Boundary Degradation In A Pipeline Steel, Denizhan Yavas, Pratyush Mishra, Abdullah Alshehri, Pranav Shrotriya, Kurt R. Hebert, Ashraf F. Bastawros
Aerospace Engineering Publications
High-strength low-alloy steels used for oil and gas pipelines are vulnerable to intergranular stress corrosion cracking in moderately alkaline soils. The mechanism of corrosion-induced embrittlement under such conditions is not yet understood. Nanoindentation was used to detect localized degradation of mechanical properties near internal grain boundaries of X-70 steel undergoing intergranular corrosion at active dissolution potentials at pH 8.2. The measurements identified a one-micron thick mechanically-degraded layer with 25% reduced hardness near corroded grain boundaries. It is suggested that the corrosion process may introduce an active softening agent, possibly non-equilibrium lattice vacancies generated by oxidation.
Assessment And Comparison Of Aviation Manufacturing Industries Throughout Mexico And Brazil, 2018 Embry-Riddle Aeronautical University
Assessment And Comparison Of Aviation Manufacturing Industries Throughout Mexico And Brazil, Omar E. Morsi, Kelly A. Whealan-George, Aaron D. Clevenger
International Journal of Aviation, Aeronautics, and Aerospace
This literature review serves to provide insight and understanding in regards to the evolving aviation manufacturing industry throughout the globe and more specifically, Mexico and Brazil. Increased demand for aircraft units both in the commercial and private sectors have led to unprecedented expansions in aircraft manufacturing across the industry. In order to illuminate certain potentials and current growth levels of such industries, this review will delve into an array of information and specifications in regards to economic, political, and cultural influences throughout both Mexican and Brazilian markets respectively. In conclusion, the review will identify the transformation of an aviation manufacturing ...
Numerical Analysis Of Aerodynamic Noise Mitigation Via Leading Edge Serrations For A Rod–Airfoil Configuration, 2018 Iowa State University
Numerical Analysis Of Aerodynamic Noise Mitigation Via Leading Edge Serrations For A Rod–Airfoil Configuration, Bharat Raj Agrawal, Anupam Sharma
Noise produced by aerodynamic interaction between a circular cylinder (rod) and an airfoil in a tandem arrangement is investigated numerically using incompressible large eddy simulations. Quasi-periodic shedding from the rod and the resulting wake impinges on the airfoil to produce unsteady loads on the two geometries. These unsteady loads act as sources of aerodynamic sound and the sound radiates to the far-field with a dipole directivity. The airfoil is set at zero angle of attack for the simulations and the Reynolds number based on the rod diameter is Red = 48 K. Comparisons with experimental measurements are made for (a) mean ...
Investigation Of 2195 And 2219 Post Weld Heat Treatments For Additive Friction Stir Lap Welds, 2017 University of New Orleans
Investigation Of 2195 And 2219 Post Weld Heat Treatments For Additive Friction Stir Lap Welds, Matthew Champagne
University of New Orleans Theses and Dissertations
To evaluate potential uses for friction stir welding in additive manufacturing, two separate parts were fabricated, one of 2195-T84 and the other 2219-T87, utilizing fixed pin techniques and additive lap welds. The parts were cut into samples, artificially aged and subjected to Rockwell hardness (HRB), Vickers hardness, micrographic photography, and metallographic imaging on both pre- and post- heat treatment. Additionally, tensile testing was performed on the heat-treated samples. A comparisons of test results showed a minimal increase in the yield strength of the 2195-T84 samples compared to as-welded tensile results obtained from a previous project. The ultimate tensile strength was ...
Pressure Self-Focusing Effect And Novel Methods For Increasing The Maximum Pressure In Traditional And Rotational Diamond Anvil Cells, Biao Feng, Valery I. Levitas
Aerospace Engineering Publications
The main principles of producing a region near the center of a sample, compressed in a diamond anvil cell (DAC), with a very high pressure gradient and, consequently, with high pressure are predicted theoretically. The revealed phenomenon of generating extremely high pressure gradient is called the pressure self-focusing effect. Initial analytical predictions utilized generalization of a simplified equilibrium equation. Then, the results are refined using our recent advanced model for elastoplastic material under high pressures in finite element method (FEM) simulations. The main points in producing the pressure self-focusing effect are to use beveled anvils and reach a very thin ...
Electron Yield Measurements Of High-Yield, Low-Conductivity Dielectric Materials, 2017 Utah State University
Electron Yield Measurements Of High-Yield, Low-Conductivity Dielectric Materials, Justin Christensen
All Graduate Theses and Dissertations
Materials exposed to the space plasma environment acquire electric charge, which can have harmful effects if it leads to arcing or electrostatic breakdown of important spacecraft components. In fact, spacecraft charging is the leading environmentally induced cause of spacecraft anomalies. This study focuses on measuring electron yield, a property of materials that describes how many electrons are ejected from a material under energetic electron bombardment, which can vary depending on the energy of incident electrons. Intrinsic electron yield is defined as the average number of electrons emitted per incident electron from an electrically neutral material. The specific aim of this ...
Structural Behavior Of Inflatable, Reinforced, Braided, Tubular Members, 2017 University of Maine
Structural Behavior Of Inflatable, Reinforced, Braided, Tubular Members, Joshua Clapp
Electronic Theses and Dissertations
The Hypersonic Inflatable Aerodynamic Decelerator (HIAD) system being developed by the National Aeronautics and Space Administration (NASA) is an inflatable structure composed of multiple, concentric, pressurized tori, load straps, and a thermal protection system. The HIAD overcomes limitations inherent with the use of rigid decelerators since the deployed diameter is much larger than the packed size, which makes it an enabling technology for new opportunities in space exploration. The HIAD is designed to decelerate and protect spacecraft during atmospheric re-entry. The objective of this research was to improve understanding of structural behavior of HIAD components through material testing, structural testing ...
Electrothermal Lifetime Prediction Of Polyimide Wire Insulation With Application To Aircraft, 2017 Iowa State University
Electrothermal Lifetime Prediction Of Polyimide Wire Insulation With Application To Aircraft, Peter R. Hondred, Nicola Bowler, Michael R. Kessler
This work investigates the electrothermal lifetime of a commonly used polyimide wire insulation material, Kapton®, through the use of thermogravimetry (TG) and breakdown voltage testing. From TG, an isoconversional model-free kinetic evaluation was used to obtain a relationship between the activation energies of degradation for Kapton as a function of weight loss. By relating the electrical life theory and the TG theory through the model defined by Toop (IEEE Trans. Dielectr. Electr. Insul. 1971, 6, 2), the electrothermal lifetime of Kapton has been calculated for conditions of 12 and 14.7 kV over a temperature range of 250–400°C ...
Hazard Assessment Of Meteoroid Impact For The Design Of Lunar Habitats, 2017 Purdue University
Hazard Assessment Of Meteoroid Impact For The Design Of Lunar Habitats, Herta Paola Montoya, Shirley Dyke, Julio A. Ramirez, Antonio Bobet, H. Jay Melosh, Daniel Gomez
The Summer Undergraduate Research Fellowship (SURF) Symposium
The design of self-sustaining lunar habitats is a challenge primarily due to the Moon’s lack of atmospheric protection and hazardous environment. To assure safe habitats that will lead to further lunar and space exploration, it is necessary to assess the different hazards faced on the Moon such as meteoroid impacts, extreme temperatures, and radiation. In particular, meteoroids pose a risk to lunar structures due to their high frequency of occurrence and hypervelocity impact. Continuous meteoroid impacts can harm structural elements and vital equipment compromising the well-being of lunar inhabitants. This study is focused on the hazard conceptualization and quantification ...
Using High Resolution Images To Investigate Fatigue Crack Initiation Of Alloys At The Microstructural Level, Michael P. Reinhold, Alberto Mello, Michael Sangid
The Summer Undergraduate Research Fellowship (SURF) Symposium
Microstructural features within a material dictate the material’s mechanical behavior and lead to localized strains as the sample is deformed. In order to further understand structural failure, an improved understanding of how microstructural features influence failure is necessary. Fatigue is one common mode of failure for aerospace applications, and a better understanding of the conditions of crack initiation can provide information that ultimately may increase longevity of aerospace systems. This paper investigates the hypothesis that fatigue crack initiation for a cyclically loaded sample is correlated to areas of higher localized strain. The experiment was conducted using a Ti-6Al-4V sample ...
Design Of Orbital Maneuvers With Aeroassisted Cubesatellites, 2017 University of Arkansas, Fayetteville
Design Of Orbital Maneuvers With Aeroassisted Cubesatellites, Stephanie Clark
Recent advances within the field of cube satellite technology has allowed for the possible development of a maneuver that utilizes a satellite's Low Earth Orbit (LEO) and increased atmospheric density to effectively use lift and drag to implement a noncoplanar orbital maneuver. Noncoplanar maneuvers typically require large quantities of propellant due to the large delta-v that is required. However, similar maneuvers using perturbing forces require little or no propellant to create the delta-v required. This research reported here studied on the effects of lift on orbital changes, those of noncoplanar types in particular, for small satellites without orbital maneuvering ...
Meso-Scale Imaging Of Composite Materials, 2017 Iowa State University
Meso-Scale Imaging Of Composite Materials, Robert J. Grandin, Joseph N. Gray
The performance of composite materials is controlled by the interaction between the individual components as well as the mechanical characteristics of the components themselves. Geometric structure on the meso-scale, where the length-scales are of the same order as the material granularity, plays a key role in controlling material performance and having a quantitative means of characterizing this structure is crucial in developing our understanding of NDE technique signatures of early damage states. High-resolution computed tomography (HRCT) provides an imaging capability which can resolve these structures for many composite materials. Coupling HRCT with three-dimensional physics-based image processing enables quantitative characterization of ...
Implementation Of Automated 3d Defect Detection For Low Signal-To Noise Features In Nde Data, 2017 Iowa State University
Implementation Of Automated 3d Defect Detection For Low Signal-To Noise Features In Nde Data, Robert J. Grandin, Joseph N. Gray
The need for robust defect detection in NDE applications requires the identification of subtle, low-contrast changes in measurement signals usually in very noisy data. Most algorithms rarely perform at the level of a human inspector and often, as data sets are now routinely 10+ Gigabytes, require laborious manual inspection. We present two automated defect segmentation methods, simple threshold and a binomial hypothesis test, and compare effectiveness of these approaches in noisy data with signal to noise ratios at 1:1. The defect-detection ability of our algorithm will be demonstrated on a 3D CT volume, UT C-scan data, magnetic particle images ...
Inversion Of Eddy Current Probe Impedance Data For Crack Reconstruction, 2017 University of Surrey
Inversion Of Eddy Current Probe Impedance Data For Crack Reconstruction, John Bowler, D. J. Harrison, S. J. Norton
John R. Bowler
The aim of eddy current inversion is to reconstruct an unknown flaw from probe signals measured as a function of probe position and frequency or time. In seeking the solution of an inverse problem, one can take advantage of an ability to solve forward problems by using predictions of probe signals calculated with a tentative estimate of the flaw. A well known inversion strategy adopted here for eddy current inversion, is that of varying the flaw estimate iteratively until the disparity between predicted and observed probe signals is minimized. Then the model flaw which gives the optimum predictions of the ...
Deployable Antenna For Cubesat, 2017 California Polytechnic State University, San Luis Obispo
Deployable Antenna For Cubesat, Mackenzie Thomas Lennon, Caleb Andrew Barber, David Matthew Galves
This project is a proof-of-concept ground model of a large deployable antenna designed for the small space requirements of CubeSats. This small deployment module is designed to fit a 2 m by 1 m reflective antenna inside a storage volume of with the dimensions 20 cm by 20 cm x 40 cm. The reflector will be deployed to a parabolic shape with the goal of modeling the reflector necessary for high frequency communication. Because this module is designed as a proof-of-concept for the deployable parabolic reflector specifically, no electrical components will be incorporated and will just focus on the deployment ...
Wing Deflection Analysis Of 3d Printed Wind Tunnel Models, 2017 California Polytechnic State University, San Luis Obispo
Wing Deflection Analysis Of 3d Printed Wind Tunnel Models, Matthew G. Paul
Master's Theses and Project Reports
This work investigates the feasibility of producing small scale, low aerodynamic loading wind tunnel models, using FDM 3D printing methods, that are both structurally and aerodynamically representative in the wind tunnel. To verify the applicability of this approach, a 2.07% scale model of the NASA CRM was produced, whose wings were manufacturing using a Finite Deposition Modeling 3D printer. Experimental data was compared to numerical simulations to determine percent difference in wake distribution and wingtip deflection for multiple configurations.
Numerical simulation data taken in the form of CFD and FEA was used to validate data taken in the wind ...
Study Of Knowledge-Based System (Kbs) And Decision Making Methodologies In Materials Selection For Lightweight Aircraft Metallic Structures, Pashupati R. Adhikari, Reza Mirshams
Journal of Applied Science & Engineering Technology
This paper presents an overview of knowledge-based system (KBS) in the context of decision making methodologies used in materials selection for the design of light weight aircraft metallic structures. Overall aircraft weight reduction means substantially less fuel consumption and better efficiency. Part of the solution to this problem is to find a way to reduce overall weight of metallic structures in the aircraft. Two distinct multiple criteria decision making (MCDM) methodologies are presented with examples featuring a set of short-listed materials suitable in the design of the structures. Pre-defined constraint values, mainly mechanical properties, are employed as relevant attributes satisfying ...
Study Of Custom Tool Control In Aviation And Aerospace And Selection Of Materials And Manufacturing Process, 2017 Morehead State University
Study Of Custom Tool Control In Aviation And Aerospace And Selection Of Materials And Manufacturing Process, Ethan C. Rowley
Morehead State Theses and Dissertations
A thesis presented to the faculty of the College of Business and Technology at Morehead State University in partial fulfillment of the requirements for the Degree of Master of Science by Ethan C. Rowley on April 27, 2017.
Unmanned Aircraft System-Based Structural Health Monitoring, 2017 Iowa State University
Unmanned Aircraft System-Based Structural Health Monitoring, Sam Dwyer
Symposium on Undergraduate Research and Creative Expression
While many think of unmanned aerial vehicles as only serving military purposes, their scope has widened immensely over recent years into the commercial realm, and even into consumer hands. Using unmanned aircraft systems to diagnose health problems and create risk values can ensure the safety of many expensive complex engineering systems, without the intrusion of human error. Engineered systems, such as space shuttles, infrastructure, airplanes, and even the runways they sit on go through regular fatigue, and need to be health monitored to ensure their safety in continued use. To do this, we attach imaging devices to a variety of ...
Using X-Ray Micro-Ct Scanning To Characterize Cracking In Composites, 2017 Iowa State University
Using X-Ray Micro-Ct Scanning To Characterize Cracking In Composites, Rachel Roth
Symposium on Undergraduate Research and Creative Expression
Fibrous composites are used throughout the aerospace industry with military, commercial, satellite, and space exploration applications. Composites are desired for their high specific strength and stiffness to weight ratios, as well as their malleability to produce aerodynamically efficient structures. We used computed tomography (CT) to investigate the structural integrity of two small rectangular carbon-fiber composite samples after each underwent unknown amounts of physical stress. Results revealed consistent cracking along the long edges and patterns of cracking through the center of one sample and virtually no cracking in the other sample. The results of this study will help to determine the ...